Hydrogenation of biomass-derived feedstocks for sustainable biofuel production: advances, challenges, and future directions in Sub-Saharan Africa context

Abstract

Hydrogenation controls oxygen removal, fuel stability, hydrogen intensity, and refinery compatibility in Sub-Saharan Africa (SSA), where hydrogen supply, electricity reliability, and catalyst regeneration remain constrained. This PRISMA-ScR review evaluates hydrodeoxygenation, co-hydrogenation, and microwave-assisted hydrogenation. It compares hydrogen demand, oxygen removal, yield, catalyst stability, techno-economic performance, life-cycle impacts, and deployment requirements. Lignocellulosic hydrodeoxygenation represents the highest-severity route. Representative studies reported hydrogen demand ranges from 0.04 to 0.07 kg H 2 kg -1 dry feed at 290 to 380°C and 40 to 70 bar H 2 . Oxygen removal reaches 85 to 95%, while liquid yield remains 55 to 70%. These conditions increase hydrogen exposure and regeneration demand. Triglyceride-based hydrodeoxygenation lowers hydrogen demand to 0.02 to 0.04 kg H 2 kg -1 feed and achieves conversion above 95%, with liquid yields of 70 to 80%. Co-hydrogenation lowers hydrogen demand, moderates deactivation, maintains 65 to 85% oxygen removal, and reduces processing cost relative to standalone hydrodeoxygenation. Microwave-assisted processing supports low-severity stabilization near distributed biomass sources. Laboratory evidence reports up to 62% lower global warming potential than conventional pyrolysis under low-carbon electricity. Electricity demand, field non-uniformity, catalyst instability, and scale-up constraints limit deployment. Pathway selection in SSA should balance conversion efficiency with hydrogen intensity, catalyst stability, and infrastructure exposure. Staged upgrading should link decentralized stabilization near biomass sources with centralized hydrodeoxygenation where hydrogen supply, catalyst regeneration, high-pressure infrastructure, and investment policies are available.